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Chp-10

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A BOOK

OF

BIOTECHNOLOGY

Chapt er

Chapter

10

CARBOHYDRATES

INTRODUCTION

Carbohydrates are a group of organic compounds containing the elements carbon, hydrogen, and oxygen, generally in the ratio of 1 : 2 : 1, with the general formula (CH2O)n (the n in the formula means that CH2O is repeated a certain number of times ; if 6 times, a molecule of glucose –C6H12O6 is formed.) One carbon bears a carbonyl group and the others hydroxyl groups. However, the definition of this group (as hydrates of carbon) has been broadened to include compounds containing nitrogen and sulphur, and compounds that do not conform to a strict 1 : 2 : 1 ratio of carbon, hydrogen, and oxygen. Carbohydrates, therefore, are considered to be polyhydroxy—aldehydes or polyhydroxy-ketones, and their derivatives.

The carbohydrates are derived more or less directly from carbon dioxide and water in photosynthesis. Sugar, starch, and cellulose are examples of carbohydrates that illustrate the importance of this class of compounds to life. Cellulose is the principal constituent of wood

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Chp-5

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MUSHROOM CULTURE

Chapt er

Chapter

159

5

MUSHROOM CULTURE

INTRODUCTION

Mushrooms have fascinated man since time immemorial. Some of them are a good source of food. About 2000 species of edible mushrooms have so far been reported from all over the world but only a few species like Agaricus campestris, the common field mushroom; A. bisporus, a cultivated variety of Europe and North America; Lentinus edodes, the Shii–take of Japan; and

Volvariella volvacea, the paddy straw mushroom of China and South-East Asia are being cultivated on an extensive scale. In Europe and North America, the cultivation of common field mushroom has become a large industry. In Great Britain and America large quantities of mushrooms are available for canning and food manufacture as well as for direct consumption.

Several million pounds of the Shii–take are produced annually in Japan and China. In India, large scale mushroom cultivation is in progress but is confined to a few states like Himachal

Pradesh, Tamil Nadu, and Uttar Pradesh.

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Chp-13

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Chapt er

Chapter

13

TRACER TECHNIQUE—THE USE

OF ISOTOPES AS TRACERS

INTRODUCTION

The atoms of most chemical elements exist in more than one variety. Each kind of a given element has a different atomic weight, but all of them carry the same nuclear charge. For example, there are three different kinds of magnesium atoms with atomic weights of 24, 25, and 26 respectively. Such different varieties of atoms of a given element are called isotopes.

Differences in the chemical behaviour of two isotopes of the same element are so slight as to be barely detectable, and ordinarily they cannot be separated by chemical methods. The chemical properties of all isotopes of a given element are virtually identical, because all have the same electronic configuration ; one isotope differs from another only in the constitution of the atomic nucleus which is composed of protons and neutrons.

RADIOACTIVE ISOTOPES

In addition to the stable isotopes described above, there are many radioactive isotopes of certain heavy elements such as uranium and radium occur in nature. The atoms of many elements not normally radioactive may be made so by bombardment with various types of elementary particles such as neutrons, protons, deutrons, and alpha particles. Such bombardments are usually accomplished with the aid of a cyclotron or a uranium pile reactor.

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Chapter

4

PURE CULTURE METHODS FOR THE

STUDY OF MICROORGANISMS

INTRODUCTION

The ability to determine the characteristics of a microorganism depends in large part on being able to grow pure cultures (cultures containing only that organism) of that microbe for study.

To cultivate, or culture miroorganisms it is necessary to establish a suitable environment, one in which the particular microbe can survive and reproduce. For each type of microorganism there are minimal nutritional requirements, tolerance limits for a variety of environmental factors, and optimal conditions for growth. By understanding the growth requirements of a given microbial species, it usually is possible to establish the necessary conditions in vitro

(within glass or plastic culture vessels) to support the optimal growth of that microorganism.

Cultures are routinely grown in the clinical microbiology laboratory to aid in the determination of the cause of a patient’s disease. Water quality testing laboratories culture microorganisms to determine the safety of the water supply. Various industries grow pure cultures of microorganisms in huge vessels called fermentors to produce numerous products of economic value.

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